System and method for corneal topography with flat panel display

ABSTRACT

A corneal topographer includes: a flat panel display configured to display a light pattern and to project the light pattern onto a cornea of an eye disposed on a first side of the flat panel display; an optical system disposed on a second side of the flat panel display, the optical system being configured to receive and process reflected light from the cornea that passes through the flat panel display from the cornea to the optical system; a camera configured to receive the processed reflected light from the optical system and to capture therefrom a reflected light pattern from the cornea produced in response to the projected light pattern; and one or more processors configured to execute an algorithm to compare the projected light pattern to the reflected light pattern from the cornea, and to produce a topographic map of the cornea based on a result of the comparison.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/019,763 filed on Jul. 1, 2014, hereby incorporated by reference inits entirety.

FIELD OF THE INVENTION

Embodiments of this invention generally pertain to the field of visiondiagnostics, and particularly to systems and methods for cornealtopography.

BACKGROUND

Ocular aberrations typically produce unwanted results in the form of badeyesight. Accurately characterizing these aberrations can lead toappropriate prescriptions and methods for treatment. Since typically60-70% of ocular aberrations result from imperfections in the cornea,the ability to determine the corneal topography of an eye is highlydesirable. Corneal topography is typically determined with a devicecalled a corneal topographer. A variety of corneal topographers areknown in the art, examples of which are disclosed in U.S. Pat. Nos.5,062,702, 6,634,752, and 7,976,163, which are herein incorporated byreference.

One type of corneal topographer employs a “Placido disk” system. APlacido disk system consists of a series of concentric illuminated ringsthat are reflected off the cornea and viewed with a detector array, suchas a charge-coupled device (CCD) or a video camera. Because of itssimplicity, the Placido disk topography system has been widely used formeasuring corneal topography. A key part of this system is the object ordevice surface with rings, as well as the spatial distribution and thewidth of these rings on the surface of the device. The location andwidth of the rings on the device are computed in such a way that theimage of the rings reflected off a reference sphere is a uniformdistribution of rings, i.e., rings equally spaced, and all with the samewidth. The radius of curvature of the reference sphere is made equal tothe mean radius of the cornea (about 7.8 mm). Then, the image of therings reflected off a cornea with aberrations will constitute ofdistorted rings, and from this distortion, one can obtain the shape ofthe cornea.

Many variations on the Placido disk approach for corneal topographymeasurements have been developed over the years, examples of which aredisclosed in U.S. Pat. Nos. 4,993,826 and 6,601,956, and by YobaniMejía-Barbosa et al., “Object surface for applying a modified Hartmanntest to measure corneal topography,” APPLIED OPTICS, Vol. 40, No. 31(Nov. 1, 2001) (“Mejía-Barbosa”). Mejía-Barbosa is incorporated hereinby reference for all purposes as if fully set forth herein.

One problem in many Placido disk type corneal topographers is alignmenterror, which is commonly referred to as a vertex error between thecorneal surface vertex and the design corneal vertex plane. Morespecifically, to make accurate calculations of corneal topography, thedevice expects the cornea to be located at a particular location longthe optical axis of the system with respect to the Placido lightsources. If an actual cornea that is being measured is “too close” or“too far” from the instrument or device, vertex error that will produceinaccurate corneal topography results, unless the vertex error can bedetermined and factored into the corneal topography calculations.

Another problem with Placido disk type corneal topographers is that thedata is obtained from analysis of a series of projected rings. In otherwords, a radial position of the detected ring is compared to a referenceposition and the comparison is used to determine the corneal shape.This, however, only provides radial deviations. While these areazimuthally resolved, they do not provide an adequate measure of the“skew” rays, i.e., those rays which would be deflected in an azimuthaldirection. This is an inherent limitation for a system using Placidorings topographers. The limitation is especially significant consideringthat astigmatism, one of the major classes of ocular aberrations, isknown to generate significant skew rays.

Instead of using concentric rings, other corneal topographers have beendeveloped that employ a light pattern comprising an array of lightsources provided on a surface having the shape of a conical frustrum, ahemisphere or other modified sphere, or an elongated oval and the like.This light pattern is projected onto the cornea of the eye, and cornealtopography is determined by observing the reflected light pattern ofreflected spots from the cornea, and comparing this pattern to theprojected light pattern from the light sources. In such a system andmethod of corneal topography, it is important to match each reflectedlight spot in the reflected light pattern to the projected light sourcewhich produced it so as to make an accurate comparison. This can bedifficult for corneas with highly aberrated topographies. But, suchmatching may be improved if the pattern of projected light sources couldbe reconfigured dynamically to create easily recognizable fiducials,and/or to increase the density of the reflected light sources in areaswhich map to more highly aberrated portions of the cornea.

Unfortunately, in many known corneal topographers that employ a patternof projected light sources, the pattern cannot easily be reconfigured tochange the colors, positions, shapes, sizes, and localized densities ofthe projected light spots in the pattern.

Furthermore, whether they employ Placido disks or an array of lightsources, these known conical topographers employ relatively complexlight generating structures, which typically do not easily lendthemselves to small, portable, and relatively inexpensive cornealtopography constructions that might be desirable for providing cornealtopography service to poor, remote, and rural populations.

SUMMARY OF THE INVENTION

Accordingly, it would be desirable to provide a system and method ofcorneal topography of an eye so as to obviate one or more problems dueto limitations and disadvantages of the related art.

In one aspect of the invention, an apparatus for corneal topographycomprises: a flat panel display configured to display a light patternand to project the light pattern onto a cornea of an eye disposed on afirst side of the flat panel display; an optical system disposed on asecond side of the flat panel display, the optical system beingconfigured to receive and process reflected light from the cornea thatpasses through the flat panel display from the cornea to the opticalsystem; and a camera configured to receive the processed reflected lightfrom the optical system and to capture therefrom a reflected lightpattern from the cornea produced in response to the projected lightpattern.

In some embodiments, the apparatus further comprises one or moreprocessors configured to execute an algorithm to compare the projectedlight pattern to the reflected light pattern from the cornea, and toproduce a topographic map of the cornea based on a result of thecomparison.

In some embodiments, the flat panel display is a transparent flat paneldisplay, wherein the reflected light from the cornea passes through thetransparent flat panel display to the optical system.

In some embodiments, the flat panel display has an aperture passingtherethrough, wherein the reflected light from the cornea passes throughthe aperture to the optical system.

In some embodiments, the projected light pattern comprises a pattern ofprojected light spots and the reflected light pattern from the corneacomprises a pattern of reflected light spots.

In some embodiments, the projected light spots are colored light spots,and various projected light spots have different colors to facilitateassociation of the reflected light spots with the projected light spotsfrom which they were generated.

In some versions of these embodiments, the apparatus is configured todynamically adjust the colors of the projected light spots to facilitateassociation of the reflected light spots with the projected light spotsfrom which they were generated.

In some versions of these embodiments, the projected light spots eachhave a size and shape, and at least one of the size and shape of atleast two of the projected light spots differ from each other tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated.

In some versions of these embodiments, the apparatus is configured todynamically adjust at least one of the size and shape of the projectedlight spots to facilitate association of the reflected light spots withthe projected light spots from which they were generated.

In some versions of these embodiments, the apparatus is configured todynamically adjust a local density of the projected light spots tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated to facilitate production ofthe topographic map of the cornea.

In another aspect of the invention, a method for corneal topographycomprises: projecting a light pattern from a flat panel display onto acornea of an eye disposed on a first side of the flat panel display;receiving and optically processing reflected light from the cornea thatpasses through the flat panel display via an optical system disposed ona second side of the flat panel display; receiving at a camera theoptically processed reflected light from the optical system; capturingfrom processed reflected light via the camera a reflected light patternfrom the cornea produced in response to the projected light pattern;comparing the projected light pattern to the reflected light patternfrom the cornea; and producing a topographic map of the cornea based ona result of the comparison.

In some embodiments, the flat panel display is a transparent flat paneldisplay, and the method further comprises passing the reflected lightfrom the cornea through the transparent flat panel display to theoptical system.

In some embodiments, the flat panel display has an aperture passingtherethrough, and the method further comprises passing the reflectedlight from the cornea through the aperture to the optical system.

In some embodiments, the projected light pattern comprises a pattern ofprojected light spots and the reflected light pattern from the corneacomprises a pattern of reflected light spots.

In some versions of these embodiments, the projected light spots arecolored light spots, and various projected light spots have differentcolors to facilitate association of the reflected light spots with theprojected light spots from which they were generated.

In some versions of these embodiments, the method further comprisesdynamically adjusting the colors of the projected light spots tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated.

In some versions of these embodiments, the projected light spots eachhave a size and shape, and at least one of the size and shape of atleast two of the projected light spots differ from each other tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated.

In some versions of these embodiments, the method further comprisesdynamically adjusting at least one of the size and shape of theprojected light spots to facilitate association of the reflected lightspots with the projected light spots from which they were generated.

In some versions of these embodiments, the method further comprisesdynamically adjusting a local density of the projected light spots tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated to facilitate production ofthe topographic map of the cornea.

In yet another aspect of the invention, an apparatus for cornealtopography comprises: a portable computing device, comprising: ahousing; a flat panel display connected to the housing and configured todisplay a light pattern thereon and to project the light pattern onto acornea of an eye disposed on a first side of the flat panel display, andone or more processors disposed within the housing of the portablecomputing device; an optical system disposed on a second side of thetransparent flat panel display, configured to receive and processreflected light from the cornea that passes through the flat paneldisplay; and a camera configured to receive the processed reflectedlight from the optical system and to capture therefrom a reflected lightpattern from the cornea produced in response to the projected lightpattern, wherein the one or more processors are configured to receiveimage data from the camera and to process the image data to produce atopographic map of the cornea.

In some embodiments, the portable computing device comprises one of asmart phone and a tablet computer.

This summary and the following description are merely exemplary,illustrative, and explanatory, and are not intended to limit, but toprovide further explanation of the invention as claimed. Additionalfeatures, aspects, objects and advantages of embodiments of thisinvention are set forth in the descriptions, drawings, and the claims,and in part, will be apparent from the drawings and detaileddescription, or may be learned by practice. The claims are incorporatedby reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by referring to thefollowing detailed description that sets forth illustrative embodimentsusing principles of the invention, as well as to the accompanyingdrawings of which:

FIG. 1A shows a side view of a first embodiment of a system formeasuring corneal topography of an eye.

FIG. 1B illustrates a perspective view of the first embodiment of asystem for measuring corneal topography of an eye.

FIG. 1C illustrates a partial cutaway perspective view of the firstembodiment of a system for corneal topography of an eye.

FIG. 2 illustrates rays for a projected light spot and a reflected lightspot in the system of FIGS. 1A-C.

FIG. 3 illustrates rays for a reflected light spot in the system ofFIGS. 1A-C.

FIG. 4 illustrates an example of an idealized pattern of light spotsproduced on a camera or detector array in the system of FIGS. 1A-C.

FIG. 5 illustrates an example of a non-idealized pattern of light spotsproduced on a camera or detector array in the system of FIGS. 1A-C.

FIG. 6 is a flowchart of a method of corneal topography.

FIG. 7 illustrates a perspective view of a second embodiment of a systemfor corneal topography of an eye.

FIG. 8 illustrates a side view of a third embodiment of a system formeasuring corneal topography of an eye.

FIG. 9 illustrates a perspective view of the third embodiment of asystem for measuring corneal topography of an eye.

DETAILED DESCRIPTION

As discussed above, it would be desirable to provide a system and methodfor corneal topography which may have some advantages compared toexisting systems and methods. The following description describesvarious embodiments of the present invention. For purposes ofexplanation, specific configurations and details are set forth so as toprovide a thorough understanding of the embodiments. It will also,however, be apparent to one skilled in the art that embodiments of thepresent invention can be practiced without certain specific details.Further, to avoid obscuring the embodiment being described, variouswell-known features may be omitted or simplified in the description.

FIG. 1A shows a side view of a first embodiment of a system 1000 formeasuring corneal topography of an eye 100. FIG. 1B illustrates aperspective view of system 1000, and FIG. 1C illustrates a partialcutaway perspective view of system 1000.

System 1000 comprises a flat panel display 1100 having a first surface1102 and a second surface 1104; a camera or detector array 1400; and anoptical system 1700 disposed on a along a central axis 1002 passing flatpanel display 1100. The eye 100 is disposed opposite first surface 1102on a first side of flat panel display 1100 and optical system 1700disposed opposite second surface 1102 on a second side of flat paneldisplay 1100. Optical system 1700 comprises a first optical element(e.g., a lens) 1740, a structure including a telecentric aperture (orstop) 1780, and a second optical element (e.g., lens) 1742. It will beappreciated by those of skill in the art that the lenses 1742, 1744, orany of the other lenses discussed herein, may be replaced orsupplemented by another type of converging or diverging optical element,such as a diffractive optical element. In some embodiments, opticalsystem 1700 may be mounted or provided in a tube which is mounted toflat panel display 1100 by a mounting bracket 150, and may be mounted toan instrument chassis or body via a mounting plate 160.

Camera 1400 may comprise a charge coupled device (CCD), a complementarymetal oxide semiconductor (CMOS) array, or another electronicphotosensitive device.

System 1000 also one or more processors 1410 which may be connected toan output of camera 1400 via a connector 190. Processor(s) 1410 may haveassociated therewith volatile and/or nonvolatile memory or other storagemedia, an operating system, executable code, a user interface includingfor example, keyboard, mouse, trackball, touchscreen, etc.), and likecomponents of known processor(s). In some embodiments, processor(s) 1410may be embodied in a personal computer. Some embodiments of a system1000 for measuring corneal topography of an eye 100 may output data fromconnector 190 to one or more external processor(s) 1410 which may beprovided separately from system 1000. In that case, processor(s) 1410may be embodied in a portable device such as a tablet computing deviceor a smartphone which can be connected to the output of camera 1400 viaconnector 190.

Beneficially, in some embodiments system 1000 may further include otherelements not shown in FIGS. 1A-1C, which may include a fixation target,a movable patient alignment stage, one or more eye illumination devices,a wavefront aberrometer (for example including a Shack-Hartmannwavefront sensor), a user interface etc.

In system 1000, flat panel display 1100 comprises a transparent colordisplay device, such as a transparent color liquid crystal display (LCD)device. Beneficially, flat panel display 1100 may include other standarddisplay components, such as driver circuitry, buffer memory, etc.

System 1000 measures the curvature and shape of the cornea of eye 100.Light for this measurement is provided by light spots 1122. As can beseen in FIGS. 1B and 1C, in operation flat panel display 1100 produces alight pattern 1120 comprising a plurality of individually controllablelight spots 1122 by illuminating corresponding pixels of flat paneldisplay 1100. Here, a “light spot” means an area of locally increasedelectromagnetic radiation in or near the visible band of theelectromagnetic spectrum, for example, in the infrared, near infrared,or ultraviolet bands of electromagnetic radiation. As used herein, theterm “light” means electromagnetic radiation in or near the visible bandof the electromagnetic spectrum, for example, in the infrared, nearinfrared, or ultraviolet bands of electromagnetic radiation.

In normal use, an operator may adjust a position or alignment of system1000 in XY and Z directions to align the patient according to camera1400. At this time, an operator may see an image of the iris of eye 100.The cornea generally magnifies and slightly displaces the image from thephysical location of the iris. So the alignment may actually be done tothe entrance pupil of the eye.

Light spots 1122 of light pattern 1120 are projected from flat paneldisplay 1100 onto the cornea of eye 100, which is disposed on the firstside of flat panel display 1100. In turn, cornea 100 reflects the lightspots generally back toward flat panel display 1100, as described ingreater detail below. Images of the individual projected light spot 1122appear as reflected light spots on camera 1400, which is disposed on thesecond side of flat panel display 1100.

In some embodiments, flat panel display 1100 may include an input forreceiving display data and control signals from an external processor,which may be processor 1410, for generating the projected light pattern1120. Beneficially, flat panel display 1100 may be controlled to changethe colors, positions, shapes, sizes, and localized densities ofprojected light spots 1122 in virtually any way desired, for example inresponse to data and control signals received from processor 1410, asdescribed in greater detail below. In particular, the colors, positions,shapes, sizes, and localized densities of projected light spots 1112 maybe varied for corneal topography of eye 100, in particular to facilitatematching of projected light spots 1122 to reflected light spots whichpass through optical system 1700 and appear on camera 1400.

As noted above, cornea 100 reflects the projected light spots generallyback toward flat panel display 1100.

FIG. 2 illustrates rays for a projected light spot 1122A and a reflectedlight spot in system 1000. As shown in FIG. 2, rays of light fromprojected light spot 1122A which are reflected by the cornea of eye 100back toward flat display panel 1100 at a wide range of angles. Notably,some of the rays are reflected back toward flat display panel 1100generally along optical axis 1002 of optical system 1700, while otherreflected rays diverge at a wide range of angles with respect to opticalaxis 1002. The structure including telecentric aperture 1780 ensuresthat only those reflected rays from projected light spot 1122A whichreturn from the cornea of eye 100 along optical axis 1002, or at anarrow angle with respect to optical axis 1002, pass through opticalsystem 700 to reach camera 1400 and thereby produce a reflected lightspot at camera 1400. This same phenomenon holds true for each projectedlight spot 1122 of projected light pattern 1120.

The diameter of telecentric aperture 1780 may be selected to determinehow much light from any particular projected light spot 1122 is sampled.If aperture 1780 is made too large, there may be too much overlapbetween the individual images of the individual projected light spot1122 for accurate calculation of corneal shape. However, if aperture1780 is made too small, not enough light reaches detector array 1400 fora usable image to form. In one embodiment, a practical size for aperture1780 may be between 1 and 4 mm.

Beneficially, aperture 1780 may be selected such that it is the onlyaperture that restricts how much light reaches detector array 1400.Deviations from that can result in departures from telecentricity andconsequent miscalculations of the shape of the cornea

FIG. 3 illustrates rays for a reflected light spot in system 1000. InFIG. 3, the diameter of telecentric aperture 1780 is denoted as “d” andthe distance between first lens 1740 and telecentric aperture 1780 isdenoted as “D.” The aperture diameter d and the distance D determine theacceptance angle θ of light rays that will be allowed to pass throughaperture 1780.

In one example embodiment, d may be 3 mm, D may be 74 mm, and in thatcase may be 2.35°. Because of the typical curvature of a corneal (radiusof curvature˜8 mm), the area that produces such a small ray bundlehaving an angular range of 2.35° when mapped back on to the cornea isrelatively small, allowing system 1000 to image small light spots thathave reflected off the cornea and traveled through telecentric aperture1780.

Aperture 1780 may influence the operation of system 1000 in severalways.

First, the size of aperture 1780 sets the solid angle of rays that canbe accepted and passed to camera 1400. This solid angle in turn sets thearea of the corneal surface that is sampled by any given projected lightspot 1122. This may be understood by thinking of the image of a givenprojected light spot 1122 to be located as a virtual image posterior tothe corneal surface. Projecting forward from this spot image is a coneof rays; the solid angle that camera 1400 can “see.” The intersection ofthis cone with the cornea surface defines the area of that surfacesampled by the light source spot. So, setting the size of aperture 1780localizes the area of the cornea that a given projected light spot 1122samples.

Second, because the sampled area size is set by the size of aperture1780, it sets the amount of light that any single projected light spot1122 deposits on detector array 1400. Thus, if aperture 1780 is made toosmall, the spots images are too dim.

Third, the size of aperture 1780 sets the depth of focus of camera 1400.If aperture 1780 is too large and the virtual images created by thecornea lie in different planes due to the fact that the power of thecornea, i.e. its curvature, is different in different areas, it becomeshard to get all images in sharp enough focus on detector array 1400 toachieve good image processing results. This can be a problem whenmeasuring an eye 100 which exhibits keratoconus.

FIG. 4 illustrates an example of an idealized reflected light pattern4000 of idealized reflected light spots 4002 produced on camera 1400 insystem 1000. Beneficially, idealized reflected light spots 4002 ofidealized reflected light pattern 4000 may be substantially uniformlydistributed at camera 1400. Idealized reflected light pattern 4000 maybe a light pattern which is produced in response to projecting projectedlight pattern 1120 onto an ideal cornea (that is, a cornea having anideal, or nominal shape).

There are several reasons for wanting a uniform grid produced at camera1400. If a reference surface (e.g., an idealized cornea, a sphere withROC=8.0 mm, etc.) could produce the pattern of FIG. 4, for example, oncamera 1400, this could facilitate easier reconstruction of the cornealtopography, since the expected spots for a “reference eye” will be on agrid, and small deviations might easily lead to simple reconstructionmethods. Furthermore, with the spot pattern being close to a grid, thespot location algorithm becomes much simpler and might easily be tackledwith a difference image calculated from an image with and without firstlight sources 1200 turned-on, followed by centroiding algorithms basedon predefined areas of interest (AOI). An additional translationcalculation might be needed prior to AOI-based centroiding to accountfor system misalignment.

When performing corneal topography on a real cornea, however, in generalthe reflected light spots do not all appear at the same locations oncamera 1400 as idealized reflected light spots 4002. FIG. 5 illustratesan example of a non-idealized reflected light pattern 5000 ofnon-idealized reflected light spots 5002 produced on camera or detectorarray 1400 in system 1000.

The differences between the locations where reflected light spots 5002appear on camera 1400 and the locations where the correspondingidealized reflected light spots 4002 from the same projected light spots1122 would have appeared are produced by aberrations in the cornealtopograph. Corneal aberrations can also change the shape of reflectedlight spots 5002.

Accordingly, in operation processor(s) 1410 may reconstruct the cornealtopograph from the image data output by camera 1400 indicating theshapes and/or locations of reflected light spots 5002 on camera 1400,and a priori knowledge of the shapes and/or locations where thecorresponding idealized reflected light spots 4002 from the sameprojected light spots 1122 would have appeared. Put another way,processor(s) 1410 may determine the locations and/or shapes of reflectedlight spots 5002 on detector array 1400, and compares these locationsand/or shapes to those expected for a standard or model cornea, therebyallowing processor 1410 to determine the corneal topography of eye 100,employing one of various known algorithms However, to employ thesealgorithms, the non-idealized reflected light spots 5002 should beaccurately mapped to the original projected light spots 1122 whichproduced it.

In some embodiments, processor(s) 1410 may employ pattern recognition(correlation based) on the image data produced by camera 1400. However,when the corneal aberration is severe, it may be difficult to matchreflected light spots 5002 to the projected light spots 1122 whichproduced them.

In some embodiments, unique fiducials associated with known light spotlocations may be employed a basis for light spot association. Towardthis end, beneficially, the colors, positions, shapes, sizes, andlocalized densities of projected light spots 1112 may be varied forcorneal topography of eye 100, in particular to facilitate matching ofprojected light spots 1122 to reflected light spots 5002. Furthermore,the density of projected light spots 1112 corresponding to regions ofhigh aberration in the corneal topograph may be increased dynamicallyand easily via flat panel display 1100 to further facilitate matching ofprojected light spots 1122 to reflected light spots 5002.

FIG. 6 is a flowchart of a method 600 of corneal topography. Method 600may be performed by system 1000.

An operation 610 includes projecting a light pattern from a flat paneldisplay onto a cornea of an eye disposed on a first side of the flatpanel display.

An operation 620 includes receiving and processing reflected light fromthe cornea that passes through the flat panel display via an opticalsystem disposed on a second side of the flat panel display. When system1000 is employed, this may include passing reflected light from thecornea which passes through a transparent flat panel display.

An operation 630 includes receiving at a camera the processed reflectedlight from the optical system.

An operation 640 includes capturing via the camera a reflected lightpattern from the cornea produced in response to the projected lightpattern.

An operation 650 includes comparing the projected light pattern to thereflected light pattern. In some embodiments, this may be done bycomparing the reflected light pattern to an idealized expected reflectedlight pattern which would be produced by the projected light pattern inthe case of a model or idealized corneal surface. In particular,operation 650 may include comparing locations and/or shapes of reflectedlight spots to those expected for a standard or model cornea.

An operation 660 includes producing a topographic map of the corneabased on the comparison performed in operation 650.

FIG. 7 illustrates a perspective view of a second embodiment of a system7000 for corneal topography of an eye. System 7000 is constructedsimilarly to, and operates similarly to, system 1000 described above indetail, so only differences therebetween will be discussed.

System 7000 includes a flat panel display 7100 which has an aperture7150 passing therethrough, wherein the reflected light from the corneapasses through aperture 7150 to optical system 1700. Accordingly, flatpanel display 7100 need not be transparent. In various embodiments, flatpanel display 7100 may comprise a liquid crystal display (LCD) device,an organic light emitting diode (OLED) display device, or other suitabledisplay device.

FIG. 8 illustrates a side view of a third embodiment of a system 8000for measuring corneal topography of an eye. FIG. 9 illustrates aperspective view of system 8000. System 8000 is constructed similarlyto, and operates similarly to, system 1000 described above in detail, soonly differences therebetween will be discussed.

System 8000 includes a portable computing device 8050 with housing 8110and flat display panel 8100. In some implementations, portable computingdevice 8050 may comprise a smart phone or a tablet device. In someimplementations, flat panel display 8100 may be a touchscreen. In someimplementations, flat panel display 8100 may be a transparent LCDdisplay, similarly to flat panel display 1100. In some implementations,flat panel display 8100 may have an aperture passing therethrough,wherein the reflected light from the cornea of eye 100 passes throughthe aperture to optical system 1700. In some embodiments, portablecomputing device 8050 may include one or more processor(s) andassociated memory, which may include volatile memory and nonvolatilememory. Portable computing device 8050 may include an operating system,executable code, a user interface (e.g., keyboard, mouse, trackball,touchscreen, etc.), and other elements which may be found in smartphones and/or tablets, such as a wireless communications transceiver, apower supply, one or more data connectors 8055, front and/or rear facingcameras, etc.

Also, in system 8000, the optical system is simplified to comprise asingle lens 8740. In portable computing device 8050, flat panel display8100 is connected to housing 8110 and configured to display a lightpattern 8120 thereon and to project light pattern 8120 onto the corneaof eye 100 which disposed on a first side of flat panel display 8100 andportable computing device 8050. Camera 1400 is disposed on a second sideof flat panel display 8100 and portable computing device 8050.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Other variations are within the concept, scope, or spirit of the presentinvention. While the invention is susceptible to various modificationsand alternative constructions, certain illustrated embodiments of theinvention are shown in the drawings, and have been described above in anexemplary form with a certain degree of particularly. Those of ordinaryskill in the art will understand, however, that the embodiments areprovided by way of example only, and that various variations can be madewithout departing from the spirit or scope of the invention. Thus, thereis no intention to limit the invention to the specific form or formsdisclosed. Rather, it is intended that this disclosure cover allmodifications, alternative constructions, changes, substitutions,variations, as well as the combinations and arrangements of parts,structures, and steps that come within the spirit and scope of theinvention as generally expressed by the following claims and theirequivalents.

1. An apparatus, comprising: a flat panel display having a plurality ofpixels and configured to display a light pattern formed by illuminationof some of the pixels and to project the light pattern onto a cornea ofan eye disposed on a first side of the flat panel display; an opticalsystem disposed on a second side of the flat panel display, the opticalsystem being configured to receive and process reflected light from thecornea that passes through the flat panel display from the cornea to theoptical system; and a camera configured to receive the processedreflected light from the optical system and to capture therefrom areflected light pattern from the cornea produced in response to theprojected light pattern.
 2. The apparatus of claim 1, furthercomprising: one or more processors configured to execute an algorithm tocompare the projected light pattern to the reflected light pattern fromthe cornea, and to produce a topographic map of the cornea based on aresult of the comparison.
 3. The apparatus of claim 1, wherein the flatpanel display is a transparent flat panel display, and wherein thereflected light from the cornea passes through the transparent flatpanel display to the optical system.
 4. The apparatus of claim 1,wherein the flat panel display has an aperture passing therethrough, andwherein the reflected light from the cornea passes through the apertureto the optical system.
 5. The apparatus of claim 1, wherein theprojected light pattern comprises a pattern of projected light spots andthe reflected light pattern from the cornea comprises a pattern ofreflected light spots.
 6. The apparatus of claim 5, wherein theprojected light spots are colored light spots, and wherein variousprojected light spots have different colors to facilitate association ofthe reflected light spots with the projected light spots from which theywere generated.
 7. The apparatus of claim 6, wherein the apparatus isconfigured to dynamically adjust the colors of the projected light spotsto facilitate association of the reflected light spots with theprojected light spots from which they were generated.
 8. The apparatusof claim 5, wherein the projected light spots each have a size andshape, and wherein at least one of the size and shape of at least two ofthe projected light spots differ from each other to facilitateassociation of the reflected light spots with the projected light spotsfrom which they were generated.
 9. The apparatus of claim 8, wherein theapparatus is configured to dynamically adjust at least one of the sizeand shape of the projected light spots to facilitate association of thereflected light spots with the projected light spots from which theywere generated.
 10. The apparatus of claim 5, wherein the apparatus isconfigured to dynamically adjust a local density of the projected lightspots to facilitate association of the reflected light spots with theprojected light spots from which they were generated to facilitateproduction of the topographic map of the cornea.
 11. A method,comprising: providing a flat panel display having a plurality of pixels;projecting a light pattern, formed by illumination of some of the pixelsof the flat panel display, from the flat panel display onto a cornea ofan eye disposed on a first side of the flat panel display; receiving andoptically processing reflected light from the cornea that passes throughthe flat panel display via an optical system disposed on a second sideof the flat panel display; receiving at a camera the optically processedreflected light from the optical system; capturing from processedreflected light via the camera a reflected light pattern from the corneaproduced in response to the projected light pattern; comparing theprojected light pattern to the reflected light pattern from the cornea;and producing a topographic map of the cornea based on a result of thecomparison.
 12. The method of claim 11, wherein the flat panel displayis a transparent flat panel display, the method further comprisingpassing the reflected light from the cornea through the transparent flatpanel display to the optical system.
 13. The method of claim 11, whereinthe flat panel display has an aperture passing therethrough, the methodfurther comprising passing the reflected light from the cornea throughthe aperture to the optical system.
 14. The method of claim 11, whereinthe projected light pattern comprises a pattern of projected light spotsand the reflected light pattern from the cornea comprises a pattern ofreflected light spots.
 15. The method of claim 14, wherein the projectedlight spots are colored light spots, and wherein various projected lightspots have different colors to facilitate association of the reflectedlight spots with the projected light spots from which they weregenerated.
 16. The method of claim 15, further comprising: dynamicallyadjusting the colors of the projected light spots to facilitateassociation of the reflected light spots with the projected light spotsfrom which they were generated.
 17. The method of claim 14, wherein theprojected light spots each have a size and shape, and wherein at leastone of the size and shape of at least two of the projected light spotsdiffer from each other to facilitate association of the reflected lightspots with the projected light spots from which they were generated. 18.The method of claim 17, further comprising: dynamically adjusting atleast one of the size and shape of the projected light spots tofacilitate association of the reflected light spots with the projectedlight spots from which they were generated.
 19. The method of claim 18,further comprising: dynamically adjusting a local density of theprojected light spots to facilitate association of the reflected lightspots with the projected light spots from which they were generated tofacilitate production of the topographic map of the cornea.
 20. Anapparatus, comprising: a portable computing device, comprising: ahousing; a flat panel display having a plurality of pixels and connectedto the housing and configured to display a light pattern thereon formedby illumination of some of the pixels and to project the light patternonto a cornea of an eye disposed on a first side of the flat paneldisplay, and one or more processors disposed within the housing of theportable computing device; an optical system disposed on a second sideof the transparent flat panel display, configured to receive and processreflected light from the cornea that passes through the flat paneldisplay; and a camera configured to receive the processed reflectedlight from the optical system and to capture therefrom a reflected lightpattern from the cornea produced in response to the projected lightpattern, wherein the one or more processors are configured to receiveimage data from the camera and to process the image data to produce atopographic map of the cornea.
 21. The apparatus of claim 20, whereinthe portable computing device comprises one of a smart phone and atablet computer.
 22. The apparatus of claim 21, wherein the one of thesmart phone and the tablet computer includes the flat panel display. 23.The apparatus of claim 22, wherein the flat panel display is atransparent flat panel display, and wherein the reflected light from thecornea passes through the transparent flat panel display to the opticalsystem.
 24. The apparatus of claim 22, wherein the flat panel displayhas an aperture passing therethrough, and wherein the reflected lightfrom the cornea passes through the aperture to the optical system.